DESCRIPTION (Taken directly from the application) Cystic Fibrosis (CF) is the most common lethal genetic disease of Caucasians and is the result of a single gene autosomal recessive disorder. Hopes for curing CF are currently riding on experimental gene therapy procedures in which a normal CF gene is permanently introduced into the lungs of affected individuals. The human parvovirus, adeno-associated virus (AAV), shows significant promise as a gene therapy vector. AAV is naturally defective, nonpathogenic and relatively easily to manipulate. In the absence of helper virus infection, the wild-type form of the virus integrates its genome into the long arm of chromosome 19. AAV is capable of successful CF gene delivery to rabbit lungs. Buoyed by the very early successes of gene delivery in animal systems, a Phase I clinical trial to deliver the human cystic fibrosis transmembrane regulator (CFTR) cDNA into CF patient lungs is imminent. Although much is known about the biology of AAV when grown in tissue culture cells, very little is known about the potential effects (both good and bad) of AAV gene therapy vectors. Only a handful of reports have appeared in the literature describing in vivo gene delivery to animal models. A vast amount of information about AAV gene therapy vectors remains to be uncovered before this exciting vector system should be used on a wide-spread basis in humans. To further develop and characterize AAV vectors we will study transgene delivery to mouse lungs. The aspects that we will study include: efficiency and longevity of expression, targeted cells, pharmacological enhancement of expression, the use of various gene promoters, neonatal gene delivery, repeated vector delivery and host responses. We have recently found that the AAV Rep78 protein, which is believed to be essential in establishment of latency, is covalently associated with virion DNA. We will study the potential of this particle-associated Rep78 to mediate vector integration. These experiments will provide essential information regarding the safety and efficacy of AAV vectors and lead to more widespread use of this important vector system.